Yearly testing is the baseline for every private well in the US. Private wells aren't regulated by the EPA the way municipal water is. No one checks the water unless the homeowner does. The annual test catches bacteria from a cracked casing or a nearby septic problem before anyone gets sick, and catches rising nitrates before they reach a dangerous level for infants and pregnant women. Skipping years means you find out something is wrong only when someone is already sick.
Quick schedule
- Yearly: total coliform bacteria, nitrates, total dissolved solids (TDS), and pH.
- Every 3 to 5 years: broader chemical panel (arsenic, lead, radon, pesticides, VOCs, depending on local risk).
- Right after any of these events: retest right away.
- Sudden change in taste, smell, or color of the water.
- Flooding near the well.
- A nearby septic system problem (yours or a neighbor's).
- Land disturbance, mining, or chemical spill in the area.
- Major repair to the well, pump, or plumbing.
- Someone in the household gets recurring stomach issues with no other cause.
- More often: baby, pregnancy, immunocompromised household member, or known local contamination risks (agriculture, industrial, mining).
What each test tells you
- Total coliform. A group of bacteria found in soil, plants, and the digestive systems of warm-blooded animals. Coliform in well water doesn't always mean something is making you sick, but it means a path exists for surface contamination to reach the water (cracked casing, bad seal, surface runoff). Almost always solvable once identified.
- E. coli. A specific type of coliform that confirms fecal contamination. Action signal.
- Nitrate. Levels above 10 mg/L are dangerous for infants under 6 months (can cause methemoglobinemia, "blue baby syndrome") and concerning for pregnant women. Nitrate sources include septic systems, fertilizer runoff, animal waste.
- pH. Outside roughly 6.5 to 8.5 can corrode pipes or scale fixtures.
- Total dissolved solids (TDS). A general water-quality indicator. High TDS often signals other things to investigate.
- Arsenic. Naturally occurring in groundwater in many US regions, including parts of the Northeast, Mountain West, and Southwest. Long-term exposure causes serious health problems.
- Lead. Usually from plumbing components rather than the well itself, but worth testing if the home has older plumbing.
- Radon. Common in granite-bedrock regions. Long-term inhalation (from showers) and ingestion are health risks.
- Pesticides, VOCs, heavy metals. Test based on local risks (agricultural runoff, old industrial sites, gas stations, dry cleaners nearby).
How to get the water tested
- Contact your county or state health department. Many offer free or low-cost coliform and nitrate testing for private wells. Ask which lab they use and what they recommend testing for in your area.
- Or order a kit from a state-certified drinking water lab. Look for "certified by the state primacy agency" or NELAP-accredited labs.
- Follow the sample instructions precisely. Coliform tests are sensitive to how the sample is taken. Wash hands, use the supplied sterile bottle, don't touch the inside of the cap, sample from a cold-water tap closest to the well (often a basement faucet or outdoor spigot).
- Get the sample to the lab fast. Most coliform samples must arrive within 24 to 30 hours and stay cold.
- Read the results carefully. A "fail" on coliform doesn't always mean illness, but it means follow-up. The lab or health department will tell you what to do next.
What changes the schedule
- Local agriculture. Heavy fertilizer or manure use in the watershed raises nitrate risk. Test nitrate twice a year.
- Septic systems on your property or close neighbors. Raises coliform risk if the septic field is uphill or close.
- Older well (40+ years). Casing can crack, seals can fail. Test more often, consider a casing inspection.
- Shallow well (less than 50 feet). More vulnerable to surface contamination. Test more often.
- Recent regional events. Floods, wildfires (changes runoff patterns), nearby industrial accidents.
- New baby. Test nitrate before the baby is born and again at any major change.
Signs to test right now, regardless of the calendar
- Water tastes, smells, or looks different. Metallic, sulfur (rotten egg), earthy, fishy, oily.
- Visible particles or cloudiness that's new.
- Recurring stomach issues in the household with no other explanation.
- Pinhole leaks or unusual corrosion on copper plumbing.
- Staining on fixtures (rust, blue-green from acidic water).
- The well or septic system on your property or a close neighbor's has had recent work.
What you can do without a lab
Not much, and that's the point. Home test strips for chlorine, pH, hardness, and iron can be useful as quick checks, but they aren't accurate for coliform, nitrate, lead, arsenic, or radon. The actual health-relevant tests require a certified lab. Treat the strip tests as a "something changed, schedule a real test" signal rather than a real answer.
What to do with results
- All in range: file the report, mark the calendar for next year.
- Coliform positive: shock chlorination of the well and a follow-up test is the common protocol. A well professional usually does this. If E. coli is present, switch to bottled water for drinking and cooking until the issue is fixed.
- Elevated nitrate: investigate sources (septic, agriculture), avoid using the water for infant formula or pregnant women, consider reverse osmosis or distillation for drinking water.
- Elevated arsenic, lead, or radon: install treatment matched to the contaminant. Different treatments work for different contaminants; there's no universal filter.
Good maintenance rhythm
- Yearly: total coliform, nitrate, pH, TDS test.
- Every 3 to 5 years: broader chemical panel based on local risks.
- After any flood, wildfire runoff event, or local contamination incident: retest.
- After any change in taste, smell, color, or family health: retest.
- Before a new baby arrives: test nitrate specifically.
- Every 10 years: have a well professional inspect the casing, cap, and seal.
- Ongoing: keep contaminants away from the wellhead. No pesticides, fuel storage, or animal pens within local setback distances.